Alkene isomerization is key to the functioning of photoreceptors in the retina of mammals; a lack of specific photoreceptors leads to colour blindness, a condition suffered by John Dalton and investigated by him in the late 1700s.

Correction for ‘Constructing chiral MOFs by functionalizing 4,2′:6′,4′′-terpyridine with long-chain alkoxy domains: examples of dia nets’ by Y. Maximilian Klein et al., CrystEngComm, 2016, 18, 4704–4707, https://doi.org/10.1039/C6CE00939E.

By introducing sterically demanding substituents in the N^N ligand in [Cu(P^P)(N^N)]+, solid-state photoluminescence quantum yields of up to 72% have been achieved.

In metal coordination compounds of the divergent ligands 4,2 ':6 ',4"-terpyridine and 3,2 ':6 ',3"-terpyridine and their 4 '-functionalized derivatives, the central pyridine ring of the 4,2 ':6 ',4"-terpyridine and 3,2 ':6 ',3"-terpyridine domains is non-coordinated. We present an overview of data from the Cambridge Structural Database to assess whether there are structural similarities between the coordination compounds of 4,2 ':6 ',4"-tpy and 1,3-di(pyridin-4-yl)benzene, and between 3,2 ':6 ',3"-tpy and 1,3-di(pyridin-3-yl)benzene. Based upon structurally characterized compounds, it emerges that the coordination chemistry of ligands including one or more 4,2 ':6 ',4"-terpyridine or 3,2 ':6 ',3"-terpyridine metal-binding domains is more abundantly exemplified than that of corresponding ligands based upon 1,3-di(pyridin-4-yl)benzene and 1,3-di(pyridin-3-yl)benzene. We provide an overview of metallamacrocycles and cages, 1D-coordination polymers and 2D- and 3D-networks.

This article introduces scientific and research integrity, with a particular emphasis on its implications for the active chemical community in Switzerland. It attempts to equate research integrity to good scientific practice and presents this as benefiting the researcher, the institution, and the discipline. The concepts are developed, and current and future challenges are identified.

SrTiO3 and BaTiO3 nanoparticles (NPs) were activated using H2O2 or aqueous HNO3, and pristine and activated NPs were functionalized with a 2,2′-bipyridine phosphonic acid anchoring ligand (1), followed by reaction with RuCl3.3H2O and bpy, RhCl3.3H2O and bpy, or RuCl3.3H2O. The surface-bound metal complex functionalized NPs were used for the photogeneration of H2 from water, and their activity was compared to related systems using TiO2 NPs. The role of pH during surface complexation was found to be important. The NPs were characterized using Fourier transform infrared (FTIR) and solid-state absorption spectroscopies, thermogravimetric analysis mass spectrometry (TGA-MS), and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and the dihydrogen generation was analyzed using gas chromatography–mass spectrometry (GC-MS). Our findings indicate that extensively functionalized SrTiO3 or BaTiO3 NPs may perform better than TiO2 NPs for water reduction.

Packing motifs within structurally characterized cis-[M(bpy)2X2] (M = any metal, bpy = 2,2′-bipyridine, X = F, Cl, Br, I) coordination compounds have been investigated using data from the Cambridge Structural Database. Compounds fall into two classes: non-solvated cis-[M(bpy)2X2] moieties and those with additional lattice molecules (solvent or other molecules). A recurring packing motif is a dimeric unit involving intermolecular face-to-face π-stacking of bpy ligands and CHbpy...X contacts, although in several cases, slippage of the stacked bpy units reduces the effectiveness of the face-to-face interaction leaving the CHbpy...X contacts as the dominant crystal-packing interaction. The prevalence of the dimeric unit versus the assembly of 1D-chains in the solid state is described.

[M(bpy)3]q+ cations (bpy = 2,2′-bipyridine) are archetypical coordination entities containing chelating bidentate N,N′-donor ligands. Each propeller-shaped cation is chiral, existing as a Δ or Λ enantiomer. The supramolecular chemistry of [M(bpy)3]q+ cations in the crystal is dominated by cation-anion interactions and, to a lesser extent, weaker non-covalent interactions. Analysis of the data for [M(bpy)3]q+ salts in the Cambridge Structural Database (CSD) reveals a ubiquitous motif in which homochiral sheets of cations generate cavities for the accommodation of anions. A series of related and common motifs in the solid-state structures of [M(bpy)3]q+ salts has been identified. One of the commonest motifs comprises a hexagon of six cations with anions either in the center or lying above and/or below the centroid.

Perovskite solar cells represent an emerging and highly promising renewable energy technology. However, the most efficient perovskite solar cells critically depend on the use of lead. This represents a possible environmental concern potentially limiting the technologies' commercialization. Here, we demonstrate a facile recycling process for PbI2, the most common lead-based precursor in perovskite absorber material. The process uses only hot water to effectively extract lead from synthetic precursor mixes, plastic- and glass-based perovskites (92.6 - 100% efficiency after two extractions). When the hot extractant is cooled, crystalline PbI2 in high purity (> 95.9%) precipitated with a high yield: from glass-based perovskites, the first cycle of extraction / precipitation was sufficient to recover 94.4 ± 5.6% of Pb, whereas a second cycle yielded another 10.0 ± 5.2% Pb, making the recovery quantitative. The solid extraction residue remaining is consequently deprived of metals and may thus be disposed as non-hazardous waste. Therefore, exploiting the highly temperature-dependent solubility of PbI2 in water provides a straightforward, easy to implement way to efficiently extract lead from PSC at the end-of-life and deposit the extraction residues in a cost-effective manner, mitigating the potential risk of lead leaching at the perovskites' end-of-life.

Metal complexes used as sensitisers in dye-sensitised solar cells (DSCs) are conventionally constructed using a push-pull strategy with electron-releasing and electron-withdrawing (anchoring) ligands. In a new paradigm we have designed new DπA ligands incorporating diarylaminophenyl donor substituents and phosphonic acid anchoring groups. These new ligands function as organic dyes. For two separate classes of DπA ligands with 2,2'-bipyridine metal-binding domains, the DSCs containing the copper(i) complexes [Cu(DπA)2]+ perform better than the push-pull analogues [Cu(DD)(AA)]+. Furthermore, we have shown for the first time that the complexes [Cu(DπA)2]+ perform better than the organic DπA dye in DSCs. The synthetic studies and the device performances are rationalised with the aid of density functional theory (DFT) and time-dependent DFT (TD-DFT) studies.

Correction for 'Constructing chiral MOFs by functionalizing 4,2 ' :6 ' ,4 ' ' -terpyridine with long-chain alkoxy domains: examples of dia nets' by Y. Maximilian Klein et al., CrystEngComm, 2016, 18, 4704-4707, https://doi.org/10.1039/C6CE00939E.

The synthesis and characterization of two tritopic ligands containing a 2,2′:6′,2″-terpyridine (tpy) metal binding domain and either a 3,2′:6′,3″- or a 4,2′:6′,4″-tpy domain are detailed. The synthetic routes to these ligands involved the [Pd(dppf)Cl2]-catalyzed coupling of a boronic ester-functionalized 2,2′:6′,2″-tpy with bromo-derivatives of 3,2′:6′,3″-tpy or 4,2′:6′,4″-tpy. The 2,2′:6′,2″-tpy domains of the tritopic ligands preferentially bind Fe2+ in reactions with iron(II) salts leading to the formation of two homoleptic iron(II) complexes containing two peripheral 3,2′:6′,3″-tpy or 4,2′:6′,4″-tpy metal-binding sites, respectively. These iron(II) complexes are potentially tetratopic ligands and represent expanded versions of tetra(pyridin-4-yl)pyrazine.

Scandium (Sc), declared a critical raw material in the European Union (EU), could face further supply issues as the EU depends almost entirely on imports from China, Russia, and Ukraine. In this study, a tandem nanofiltration-solvent extraction procedure for Sc recovery from titania (TiO2) acid waste was piloted and then augmented by antisolvent crystallization. The new process, comprising advanced filtration (hydroxide precipitation, micro-, ultra-, and nanofiltration), solvent extraction, and antisolvent crystallization, was assessed in relation to material and energy inputs and benchmarked on ScF3 production. From ∼1 m3 of European acid waste containing traces of Sc (81 mg L-1), ∼13 g of Sc (43% yield, nine stages) was recovered as (NH4)3ScF6 with a purity of approximately 95%, demonstrating the technical feasibility of the approach. The production costs per kilogram of ScF3 were lower than reported market prices, which underscores a competitive process at scale. Although a few technical bottlenecks (e.g., S/L separation and electricity consumption) need to be overcome, combining advanced filtration with solvent extraction and antisolvent crystallization promises a future supply of this critical raw material from European secondary sources.

The effects of introducing bpy ligands with CH 2 CH 2 CCH substituents in the 6- and 6,6′-positions in [Cu(N^N)(P^P)] + complexes are explored; structural data are discussed in terms of CC⋯π arene interactions in compounds in the Cambridge Structural Database.

Correct photoluminescence quantum yield (PLQY) determination in the solid state is vital for numerous application fields, such as photovoltaics, solid lighting or the development of phosphors. In order to increase the limited number of suitable standards for such determinations, two new Ln(3+)-based complexes with 4 '-phenyl-2,2 ' : 6 ',2"-terpyridine gamma-[Ln(4)(OAc)(12)(ptpy)(2)] (1-Eu with europium and 1-Tb with terbium) are presented. The corresponding complexes show solid-state QYs of 58(4) % and 46(3) %, respectively, exhibiting broadband absorption in the UV range from 380-200 nm. As Ln(3+) ions in general exhibit narrow f-f transitions, spectral regions with a broadness of 20-35 nm can be checked. Both complexes have suitable thermal stability, up to 270 degrees C, and are stable with respect to air and humidity, for 1-Eu up to 75 % and for 1-Tb up to 53 % relative humidity. These complexes are altogether suitable as standards to increase the reliability of PLQY determination and proposed to be used for a relative PLQY determination in the solid state.

Analysis of the data in the Cambridge Structural Database (CSD) for compounds containing an {M(tpy)X3} motif (tpy = 2,2’:6’,2”-terpyridine, M = any metal, X = F, Cl, Br, I) reveals 17 isostructural mononuclear [M(tpy)X3] compounds crystallizing without lattice solvent; both face-to-face π-stacking of pyridine rings and C–H3/H3’…X hydrogen bonding appear to be equally important. Regardless of coordination number (CN = 6, 7 or 8) and nuclearity (mono- or dinuclear), a recurring packing feature in other compounds containing an {M(tpy)X3} unit is the presence of bifurcated Cl…H3/H3’ interactions, complemented in some cases by Cl…H5’/H3” interactions, consistent with the acidic H3, H3’, H5’, and H3” atoms of a coordinated tpy ligand. Octahedral [M(tpy)F3] complexes crystallize as hydrates with strong F…H–OH hydrogen bonding dominating the crystal packing.

Analysis of the data in the Cambridge Structural Database (CSD) for compounds containing an {M(tpy)X-3} motif (tpy = 2,2':6',2"-terpyridine, M = any metal, X = F, Cl, Br, I) reveals 17 isostructural mononuclear [M(tpy)X-3] compounds crystallizing without lattice solvent; both face-to-face p-stacking of pyridine rings and C-H3/H3' horizontal ellipsis X hydrogen bonding appear to be equally important. Regardless of coordination number (CN = 6, 7 or 8) and nuclearity (mono- or dinuclear), a recurring packing feature in other compounds containing an {M(tpy)X-3} unit is the presence of bifurcated Cl horizontal ellipsis H3/H3' interactions, complemented in some cases by Cl horizontal ellipsis H5'/H3" interactions, consistent with the acidic H3, H3', H5', and H3" atoms of a coordinated tpy ligand. Octahedral [M(tpy)F-3] complexes crystallize as hydrates with strong F horizontal ellipsis H-OH hydrogen bonding dominating the crystal packing.

Correction for 'A 3-dimensional {4(2)center dot 8(4)} lvt net built from a ditopic bis(3,2 ':6 ',3 ''-terpyridine) tecton bearing long alkyl tails' by Y. Maximilian Klein et al., CrystEngComm, 2015, 17, 2070-2073, https://doi.org/10.1039/C4CE02347A.

John Dalton is one of the pioneers who transformed chemistry into the science that we enjoy today. His name is irrevocably linked with the atomic theory that underlies our modern understanding of chemical structure. This article summarizes his life and contributions and attempts to place them in the context of the intellectual revolution that was transforming all aspects of science.

Invited for the cover of this issue are Davood Zare, Claude Piguet, Edwin C. Constable and co-workers at the University of Basel and the University of Geneva. The image depicts a [AgI L]+ intermediate about to catch a second α,α'-diimine ligand to form the stable [AgI L2 ]+ . Read the full text of the article at 10.1002/chem.202200912.